The present invention is directed to a push-push type latching switch wherein the first push by an operator on a push button changes the switch from the first state to a second state, and the switch is latched in the second state. The second push by the operator changes the switch from the second state to the first state and the switch is then latched in the first state. For this type of push-push operation, it has been found that the tactile feel or feedback to the operator as the switch is displaced is important in providing a high technology response which is readily marketable. It is additionally found to be important to provide an extremely low displacement such that the operation of the button only requires making momentary contact. The use of low displacement with a latching switch has been found particularly suitable for customer acceptance and other marketing reasons.
Previous push-push type switches have often used various camming and other arrangements to achieve the desired switching and latching operation. Previous designs have been utilized to what is commonly referred to as the "heart-in-heart" design wherein heart shaped cams are utilized to control the positioning of the switch actuator or switch contactor. However, this type of switch requires overtravel by the actuator to achieve the switching.
Other prior art devices have converted in-out push button displacement into left-right direction displacement to achieve appropriate motion between electrical contacts distinct from the in-out motion of the push button. U.S. Pat. No. 4,300,026 discloses a switch assembly wherein a plunger engages a pivotably supported member to displace electrical contacts in a left-right direction while the push button is moved in the in-out direction. U.S. Pat. No. 3,045,482 discloses another push button switch wherein a contact carrier is displaced in the left-right direction by operation of a push button in an in-out direction through a limited loss motion connection.
U.S. Pat. No. 2,994,750 discloses a snap acting switch having a pivotably mounted carrier which is snapped in the opposite direction about its pivot axis by a trip lever adapted to alternatively engage spaced seats in the carrier in response to push button displacement.
The herein invention provides a push-push type latching switch having the smallest displacement of any known switch commercially available of this type. Initial samples indicate that positive switching and latching may be obtained with an in-out displacement of the push button of only 40 thousandths of an inch (0.040 inches). Notwithstanding this small displacement, tactile feedback to the operator is additionally provided as a result of the mechanical displacement of contacts over a detent ridge separating the first position of a switch from a second position of the switch.
Furthermore, the herein described switch may be used in pairs and have a cross cancelling feature such that if one of the pair of switches is in the "on" position, then when the other switch is placed in the "on" position, the first switch is placed automatically in the "off" position. If the first switch is in the "off" position, switching of the second switch does not affect the position of the first switch.